On Sat, Jul 01, 2023 at 09:39:32AM +0300, Arseniy Krasnov wrote:
This adds copying to guest's virtio buffers from non-linear skbs. Such
skbs are created by protocol layer when MSG_ZEROCOPY flags is used. It
replaces call of 'copy_to_iter()' to 'skb_copy_datagram_iter()'- second
function can read data from non-linear skb. Also this patch uses field
'frag_off' from skb control block. This field shows current offset to
read data from skb which could be both linear or not.
Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
---
Changelog:
v4 -> v5:
* Use local variable for 'frag_off'.
* Update commit message by adding some details about 'frag_off' field.
* R-b from Bobby Eshleman removed due to patch update.
I think we should merge this patch with the previous one, since
vhost-vsock for example uses virtio_transport_stream_do_dequeue()
that we change in the previous commit, so we will break the bisection.
The patch LGTM!
Stefano
drivers/vhost/vsock.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 6578db78f0ae..cb00e0e059e4 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -114,6 +114,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
struct sk_buff *skb;
unsigned out, in;
size_t nbytes;
+ u32 frag_off;
int head;
skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
@@ -156,7 +157,8 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
}
iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
- payload_len = skb->len;
+ frag_off = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
+ payload_len = skb->len - frag_off;
hdr = virtio_vsock_hdr(skb);
/* If the packet is greater than the space available in the
@@ -197,8 +199,10 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
break;
}
- nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
- if (nbytes != payload_len) {
+ if (skb_copy_datagram_iter(skb,
+ frag_off,
+ &iov_iter,
+ payload_len)) {
kfree_skb(skb);
vq_err(vq, "Faulted on copying pkt buf\n");
break;
@@ -212,13 +216,13 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
added = true;
- skb_pull(skb, payload_len);
+ VIRTIO_VSOCK_SKB_CB(skb)->frag_off += payload_len;
total_len += payload_len;
/* If we didn't send all the payload we can requeue the packet
* to send it with the next available buffer.
*/
- if (skb->len > 0) {
+ if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off < skb->len) {
hdr->flags |= cpu_to_le32(flags_to_restore);
/* We are queueing the same skb to handle
--
2.25.1
